Classify errors by whether the trial balance detects them
Use debit and credit agreement to identify detectable imbalances, while recognising errors that leave a trial balance balanced.
Section 1.4 · Reconciliation and verification
Cambridge International AS & A Level Accounting 9706, 2026–2028 syllabus, Version 2. These lessons cover Topic 1.4 only. Practice is self-checked, not an official Cambridge grade; the separately published 2029 syllabus, timed papers and human subject-teacher review remain outstanding.
Before you begin
- Use double-entry, ledger and trial-balance knowledge from Topic 1.2. Reconciliations compare records with independent or separately maintained evidence; an unexplained difference needs investigation.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Why does a one-sided posting often make a trial balance disagree?
What you will learn
- Explain the purpose and limits of a trial balance
- Distinguish errors that affect or do not affect its agreement
- Classify the six specified errors that do not affect agreement
Agreement is a useful arithmetic check
A trial balance lists ledger balances in debit and credit columns. Equal totals provide evidence that ledger balances have been extracted and totalled consistently, but agreement does not prove that every transaction is complete, correctly classified or recorded in the right account.
A one-sided posting, a wrong-side posting or unequal debit and credit amounts can make totals disagree. Recalculate the trial balance and check ledger balancing and extraction before using the difference to search for the error.
Some errors preserve equality
An error of omission leaves out both entries. An error of commission records an item in the wrong account of the same class; an error of principle uses the wrong accounting category; an error of original entry records the same wrong amount on both sides; a complete reversal swaps both sides; and compensating errors offset each other. Each can leave debit and credit totals equal.
A balanced trial balance therefore has limits. It does not detect every error, and some errors can be material even though the totals agree. Reconcile accounts and inspect supporting evidence as separate checks.
Its benefits are a quick check of debit-credit agreement and a structured list of balances for draft statements. Its limitations are that equality cannot prove completeness, correct classification, accuracy or authorisation.
Pause and explain
A $460 expense is debited to the wrong expense account, with the credit to bank correct. What error is this most likely to be?
Worked example
A $780 credit purchase of stationery is debited to stationery expense and credited to trade payables as $870. Does the trial balance still agree, and what type of error occurred?
Show the worked solution
- Both entries are present, but each is $90 too high.
- Debits and credits remain equal because the same incorrect amount was used on both sides.
- This is an error of original entry; the trial balance does not reveal it by agreement alone.
Answer The trial balance can still agree. Both sides were recorded at $870 instead of $780, an error of original entry.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Classify each error: (a) a credit sale is omitted entirely; (b) equipment is debited to repairs, with the correct bank credit; (c) both sides of a $1,240 purchase are recorded as $1,420.
Give me a hint
Ask whether both entries exist, whether the category is wrong and whether both amounts match.
Compare my reasoning
- (a) No debit or credit is posted, so it is an error of omission.
- (b) The asset purchase is charged to an expense, so it is an error of principle.
- (c) Both sides use the same wrong amount, so it is an error of original entry.
(a) Omission; (b) principle; (c) original entry. All three can leave the trial balance in agreement.
Look for these in your work
- Each error classified
- Reason given
- Detection limit stated
A debit entry of $2,600 is posted as $260, while its credit entry is $2,600. What happens to the trial-balance totals, and what is the difference?
Give me a hint
Compare the amount missing from the debit column.
Compare my reasoning
- Debit is understated by 2,600 − 260 = $2,340.
- Credit is unchanged.
- The credit total exceeds the debit total by $2,340, before considering other errors.
The trial balance will show credits exceeding debits by $2,340, assuming no other errors.
Look for these in your work
- Difference calculated
- Direction correct
- Other-error assumption stated
A trial balance agrees, but a customer says a $1,500 credit sale is missing from the account. Explain how this can happen and name a follow-up check.
Give me a hint
Consider whether both entries might have been omitted together.
Compare my reasoning
- If the sales and receivables entries were both omitted, debit and credit totals could still agree.
- The trial balance does not detect an omission from both sides.
- Trace the customer order, dispatch record and sales invoice into the sales journal and customer account.
The entire transaction may have been omitted from both sides. Trace the dispatch and invoice through the sales records and customer ledger; agreement alone cannot rule out omission.
Look for these in your work
- Balanced omission explained
- Evidence trail proposed
- Trial-balance limitation clear
Common mistakes
- Claiming agreement proves that accounts are correct
- Confusing an error of omission with an error on one side only
- Calling every wrong account an error of principle
What can you explain now?
Which error can leave the trial balance in agreement?
Compare with the explanation
A transaction omitted from both debit and credit entries
Leaving out both equal entries preserves the equality of the totals.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Name the six errors listed in this syllabus that may not affect trial-balance agreement.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.